HISrORr of the SOCIETT. 21 



The dodrine of the fympathy of the nerves has been fo 

 much employed in accounting for the eifeds of opium, that Dr 

 Wilson judged it proper to make fome obfervations vipon it ; 

 in which he endeavours to prove, that no fuch law of the ani- 

 mal ceconomy exifls ; and that all the phenomena, which have 

 been referred to, this fuppofed law, depend on certain changes 

 taking place in the Jenjoriiim commune. 



In an appendix, he relates fome experiments, made with a view 

 to determine the manner in which tobacco a(Els on living animals. 

 From thefe experiments it appears, that the fymptoms which 

 tobacco produces, when thrown into the heart, are the fame 

 with thofe excited by its immediate application to the brain. 

 That thefe fymptoms, when the tobacco is exhibited in the for- 

 mer way, proceed from no adlion of the tobacco on the nerves 

 of the heart, but from its being conveyed along the aorta, and 

 immediately applied to the brain ; fince they do not follow its 

 inje(flion into the heart, when the aorta is previoully fecured by 

 ligature ; although it was found, that interrupting the circula- 

 tion does not unfit the nervous fyflem from undergoing the 

 change neceffary for the produdlion of fuch fymptoms. It alfo 

 appears from thefe experiments, that tobacco produces the fame 

 effecSls, though more flowly, when thrown into the ftomach and 

 inteflines as when thrown into the heart : That in the former 

 cafe, as in the latter, they are ftill to be afcribed to the tobacco 

 being received into the fanguiferous fyftem, and imrnediately 

 applied to the brain ; and that the effecfls of this drug, when it 

 acfts merely on the nerves of the part to which it is applied, do 

 not efTentially differ from thofe of any ftrong topical irritation. 

 It may alfo be colleded from thefe experiments, that the pre- 

 fence of tobacco in the fyflem, like that of opium, only affeds 

 the irritability of the mufcles of voluntary motion, when it pro- 

 duces convuliions in them ; i, e, when it is apphed in confider- 



able 



